Direct Drive Supply Air Inverter; Set Blower Speed - Lennox LGH Series Unit Information

IX-Direct Drive Supply Air Inverter
If a test and balance contractor has not commissioned the
unit, use this section to set supply air CFM.
A-Set Blower Speed
1- Use table 28 to fill in field-provided, design specified
blower CFM.
TABLE 28
Blower CFM Design Specifications
Blower Speed
Heating
Cooling High
Cooling Low
Ventilation
2- Use the following menu to enter the blower design
specified CFM into the Unit Controller. Don't press
"SAVE" until all CFM are entered. Make sure blower
CFM is within limitations shown in table 29. Refer to the
Unit Controller manual provided with unit.
SETUP > TEST & BALANCE > BLOWER
3- Once all four speeds are entered, the target (highest of
the heating and cooling settings) CFM and default
RPM will be displayed.
Note - When units are not equipped with heat, the Blower
Heat speed will not be displayed. Blower Cooling High will
be the first blower speed to appear.
4- Measure the static pressure as shown in the Blower
Start-Up section. Use the static pressure, target CFM
and blower tables to determine the RPM needed. Val­
ues in the blower table reflect the static pressures tak­
en in locations shown in figure 19.
5- Enter the RPM and repeat the previous step until the
design CFM is reached.
6- Press SAVE followed by MAIN MENU.
Note - Once the CFM settings are saved, the Unit Controller
will set all other blower CFM.
Design
Specified CFM
Page 70
B-Set Damper Minimum Position
To maintain required minimum ventilation air volumes when
the unit is in the occupied mode, two minimum damper posi­
tions must be set. The Unit Controller will open the dampers
to "Min OCP Blwr Low" when blower CFM is BELOW a "mid­
point" CFM. The Unit Controller will open the damper to "Min
OCP Blwr High" when blower CFM is at or ABOVE the "mid­
point" CFM.
The Unit Controller will calculate the "midpoint" CFM.
Set Minimum Position 1
Use the following menu in the Unit Controller to set "Min
OCP Blwr Low" for the blower CFM below the "midpoint"
CFM. When navigating into this menu, the Unit Controller
will bring on the corresponding blower speed and allow
damper position adjustment.
SETTINGS > RTU Options > EDIT PARAMETER > ENTER
DATA ID - 9 > MIN DAMPER LOW BLOWER = X.X %
Measure the intake air CFM. If the CFM is lower than the
design specified CFM for ventilation air, use the Unit Con­
troller to increase the damper percent open. If the CFM is
higher than specified, decrease the damper percent open.
Note - Intake air CFM can also be determined using the out­
door air temperature, return air temperature and mixed air
temperature. Refer to the economizer or outdoor air
damper installation instructions.
Set Minimum Position 2
Use the same menu in the Unit Controller to set "Min OCP
Blwr High" for the blower CFM above the "midpoint" CFM.
When navigating into this menu, the Unit Controller will
bring on the corresponding blower speed and allow damper
position adjustment.
SETTINGS > RTU OPTIONS > DAMPER > MIN
DAMPER POSITION BLOWER ON HIGH = X.X %
Measure the intake air CFM. If the CFM is lower than the
design specified CFM for ventilation air, use the Unit Con­
troller to increase the damper percent open. If the CFM is
higher than specified, decrease the damper percent open.
Note - Intake air CFM can also be determined using the out­
door air temperature, return air temperature and mixed air
temperature. Refer to the economizer or outdoor air
damper installation instructions.